Field of the Invention
Embodiments of the present invention relate to a display device, in particular, to a thin film transistor, an array substrate, a display device, and methods of manufacturing the thin film transistor and the array substrate.
Description of the Related Art
A thin film transistor is used as a switching element in a flat-panel display device such as liquid crystal display (LCD), organic light emitting diode (OLED) display, active matrix organic light emitting diode (AMOLED) display and the like. For example, in a common LCD, a channel layer of TFT is mainly formed of amorphous silicon layer, which has a low mobility. As the display becomes larger, resolution and high-frequency driving performance of the display are increasingly demanded, the mobility of the channel layer of TFT is thus needed to be increased.
Currently, it has been developed to use a metallic oxide, such as Ga—In—Zn—O (IGZO) film, as an active layer of TFT. The metallic oxide has a mobility which is dozens of times that of the amorphous silicon layer and exhibits an excellent semiconductor characteristic, so that charge and discharge rates of a pixel electrode by the TFT may be greatly increased, thereby increasing a response speed of the pixel, realizing a faster refresh rate and increasing a line scanning rate of the pixel significantly.
The thin film transistor having the active layer formed of IGZO generally has an etching barrier layer, that is, an insulation layer is required to be deposited on the active layer after the IGZO active layer is formed, so as to protect the metallic oxide (IGZO) layer from being damaged during a subsequent etching of source and drain metal electrodes, thereby improving a performance of TFT having metallic oxide IGZO. Thus, it requires an additional photolithographic process to form the etching barrier layer, increasing steps of the process of manufacturing the TFT.